Development of a Novel Isophorone-Derived Near-Infrared Fluorescent Probe for Specific and Visual Detection of Pb2+: Theoretical, Practical and Bioimaging Investigations

Abstract

The development of specific and visually detectable fluorophores for the accurate and rapid Pb2+ recongnization is crucial. In this study, we introduced a novel isophorone-derived fluorescent probe, (E)-2-(3-(3-formyl-4-hydroxystyryl)-5,5-dimethylcyclohex-2-en-1-ylidene)malononitrile (YSQ), rationally designed for prompt and high-quality Pb2+ detection. YSQ demonstrated noticeable fluorescence enhancement upon Pb2+ interactions, with visible color changes discernible to the naked eye in MeOH/H2O (v/v 9/1, pH 7.4, 0.2 mM). The probe YSQ achieved a quite low detection limit (LOD) of 18 nM and a high association constant of 2.93 × 105 M-1 towards Pb2+ using fluorescence titration. We proposed a binding mechanism of YSQ with Pb2+ ions, supported by the density functional theory (DFT/TD-DFT), 1H NMR titration experiments and IR analysis. In addition, a simple and affordable smartphone-supported specific Pb2+ detection technique was developed with visible color changes. Furthermore, this NIR emissive properties of YSQ offered broad potential applications in actual water sample and solid analysis, bio-imaging and test strips.

Keywords: lead ions, fluorescence probe, actual sample analysis, Cell imaging, test strip